Many perennial plants are grown for commercial purposes. Perennial plants grown for commercial purposes (referred to herein as “perennial crops”) include many fruit trees, such as apple trees, pear trees and citrus plants, fruit producing vines, such as grape vines, and trees grown for paper, pulp, wood chip or timber production. They can include temperate, sub tropical and tropical species.
Perennial crops are typically grown over large areas, e.g. in orchards or vineyards for fruit production or in forestry plantations for paper, pulp, wood chip or timber production.
Perennial crops can be affected by a variety of pests, including insects and fungi, which can reduce the growth or fruit production of the perennial crop and can result in damage or even death to the plants.
Various methods have been used to apply pesticides to perennial crops. One common method of applying pesticides to perennial crops is aerial spraying.
Insecticides such as neonicotinoids are absorbed systemically by plants through the plants root system. Similarly, fertiliser and plant food elements may be absorbed by the plant root system. Such absorption of insecticides, plant fertilizer or plant food or other compositions is effective in improving the growth of perennial plants.
Pesticides, insecticides, fertilizers and plant food have been applied to individual trees by injection into the soil at multiple locations around the tree or by injection directly into the tree. They also have been applied to seedlings as a pill deposited in the soil at the time of planting the seedlings. Further, they may be applied to citrus and apple trees as a drench on the soil surface around the tree.
These methods of application have a number of disadvantages for application to perennial crops or other perennial plants which are grown over a large area. The injection of a pesticide into the soil around each plant to be treated or injection of a pesticide or fertiliser into the plant is time consuming and labour intensive and therefore is an expensive method of applying a composition to perennial crops over large areas. Applying a drench to each plant can also be time consuming and can have adverse environmental effects as the drench may readily move from the site of application and be for example washed into waterways. The deposit of a pill in the soil at the time of planting a seeding is also time consuming and is not a method applicable for established plants. These methods of application also only allow for application at a slow speed and do not allow for easy application in heavily vegetated ground cover situations.